Swift中fallthrough的使用

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转自： http://blog.sina.com.cn/s/blog_6d01cce30101noxx.html

Swift中除了支持C中的continue,break,return,另外一种跳转关键字：fallthrough，它提供了语句跳转的一种方式

例子：

let integerToDescribe = 1

var description = "The number \(integerToDescribe) is"

switch integerToDescribe {

case 1, 3, 5, 7, 11, 13, 17, 19:

description += " a prime number, and also";

fallthrough

default :

description += " an integer"

}

println(description)//The number 1 is a prime number, and also an integer

// 如果没有其他case则直接跳转到default,另一种情况：

let integerToDescribe = 1

var description = "The number \(integerToDescribe) is"

switch integerToDescribe {

case 1, 3, 5, 7, 11, 13, 17, 19:

description += " a prime number, and also";

fallthrough

case 5:

description += " an integer"

default :

description += " finished"

}

println(description)//The number 1 is a prime number, and also an integer

// fallthrough 提供了一种让程序条件跳转执行的方式，上边的例子如果想要执行default里的操作，这样做：

let integerToDescribe = 1

var description = "The number \(integerToDescribe) is"

switch integerToDescribe {

case 1, 3, 5, 7, 11, 13, 17, 19:

description += " a prime number, and also";

fallthrough

case 5:

description += " an integer"

fallthrough

default :

description += " finished"

}

println(description)//The number 1 is a prime number, and also an integer finished

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